The present invention relates to a method for producing a polyurethane resin which forms a sheet-form article such as a synthetic leather, an artificial leather, a film, a sheet form article such as a sheet for molding, or a surface of the sheet-form article excellent in dry touch property and oleic acid-resistance. The present invention also relates to a sheet-form article.
Heretofore, polyurethane resins have been widely used for sheet-form articles such as synthetic leathers, artificial leathers, films, or sheets for molding or surface treatment of the sheet-form articles. In theses field, various feel is required for the sheet-form articles when they are touched, together with higher durability. Particularly, in the uses for wheeled vehicles and the like in which a high performance is required, a polyurethane resin having both of dry touch property and oleic acid-resistance has been desired.
Dry touch property means a feel free from so-called wet touch when a sheet-form article is touched. Hitherto, for example, a method of blending a polyurethane resin with a hard polymer or a technique for enhancing crystallinity of a polyurethane resin have been employed but these method and technique result in a defect that flexural resistance and a soft feel of a sheet-form article thereof are deteriorated.
Moreover, oleic acid-resistance is a substitute property for the durability against human sweat which comes into contact with a sheet-form article. Hitherto, so-called yellowing or hardly yellowing polyurethane resins wherein aromatic isocyanates are used have exhibited relatively satisfactory oleic acid-resistance but there is a problem of poor discoloring resistance. On the other hand, so-called yellowing-free polyurethane resins wherein aliphatic isocyanates are used are excellent in discoloring resistance but it is difficult to attain satisfactory oleic acid-resistance.
An object of the invention is to provide a method for producing a polyurethane resin excellent in discoloring resistance and also having both of dry touch property and oleic acid-resistance, which is hitherto difficult to obtain.
Another object of the present invention is to provide a resin composition comprising the polyurethane resin.
A still other object of the present invention is to provide a sheet-form article comprising the polyurethane resin.
Other objects and effects of the present invention will become apparent from the following description.
As a result of extensive studies, the present inventors have found that the above problem can be solved by using, as components of a compound having an active hydrogen-containing group, (A1) a compound having one spiro ring and active hydrogen-containing groups at both ends and (A2) an aliphatic polycarbonate polyol, and thus, have accomplished the invention.
Namely, the invention provides a method for producing a polyurethane resin which comprises reacting: (A) a compound having an active hydrogen-containing group, containing (A1) a compound having one spiro ring and active hydrogen-containing groups at both ends and (A2) an aliphatic polycarbonate polyol; (B) a polyisocyanate; and (C) a chain-extending agent, preferably a diamine compound.
The present invention also provides a polyurethane resin composition comprising the polyurethane resin.
Furthermore, the present invention also provides a sheet-form article comprising the resin or the resin composition.
In a preferred embodiment, the content of said compound (A1) is from 0.2 to 40% by weight relative to the polyurethane resin.
In another preferred embodiment, said compound is 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane.
As the compound (A1) having one spiro ring and active hydrogen-containing groups at both ends, a glycol, a diamine, or the like represented by the following formula (1) is mentioned. 
(wherein R represents an active hydrogen-containing alkyl group)
Specific examples of the glycol include 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(2-hydroxyethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(1-methyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(1-ethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(1-ethyl-1-methyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(2-hydroxyethyl-2-methyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(1-methyl-2-hydroxy-2-methylethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(1-ethyl-2-hydroxy-2-methylethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(1,1-dimethyl-2-hydroxy-2-methoxylethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(1-ethyl-1-methyl-2-hydroxy-2-methylethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, and 3,9-bis(2-hydroxypropyl)-2,4,8,10-tetraoxaspriro[5.5]undecane.
Examples of the diamine include 3,9-bis(1,1-dimethyl-2-aminoethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(2-aminoethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(1-methyl-2-aminoethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(1-ethyl-2-aminoethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(1-ethyl-1-methyl-2-aminoethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(2-aminoethyl-2-methyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(1-methyl-2-amino-2-methylethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(1-ethyl-2-amino-2-methylethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(1,1-dimethyl-2-amino-2-methylethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9-bis(1-ethyl-1-methyl-2-amino-2-methylethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane, 3,9bis(2-aminopropyl)-2,4,8,10-tetraoxaspriro[5.5]undecane and the like. Among these active hydrogen-containing group-having compounds, preferred is 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspriro[5.5]undecane.
The content of the compound (A1) having a spiro ring and active hydrogen-containing groups at both ends, in the polyurethane resin is preferably from 0.2 to 40% by weight, and the content of such a range can result in excellent dry tough property and solution stability. The most preferred content is from 0.5 to 35% by weight.
The aliphatic polycarbonate polyol (A2) for use in the invention has a constituting unit represented by the following formula (2). 
(wherein R represents an aliphatic alkylene group, preferably an aliphatic alkylene group having 4 to 20 carbon atoms, more preferably an aliphatic alkylene group having 4 to 9 atoms. Particularly preferred carbon number of the R groups in the aliphatic alkylene groups is 4 alone or a combination of 4 and 6.
For the production of the aliphatic polycarbonate polyol for use in the invention, a glycol is used as a starting material. Examples of the glycol having an aliphatic alkylene group which satisfies the requirement of the aliphatic alkylene group (R) in the constituting unit (formula (2)) of the aliphatic polycarbonate polyol (A2) in the active hydrogen-containing group-having compound of the invention include 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 2-ethyl-1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2-methyl-1,8-octanediol, 2,4-diethyl-1,5-pentanediol, 1,3-cyclohexanediol, 2,2xe2x80x2-bis(4-hydroxycyclohexyl)propane, 1,4-dimethylolcyclohexane, dipropylene glycol, polytetramethylene glycol, 2,6xe2x80x2-dihydroxyethyl hexyl ether, 2,4xe2x80x2-dihydroxyethyl butyl ether, 2,5xe2x80x2-dihydroxyethyl pentyl ether, 2,3xe2x80x2-dihydroxy-2,2xe2x80x2-dimethylpropyl ether, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-pentyl-2-propyl-1,3-propanediol, 2-butyl-2-hexyl-1,3-propnaediol, 2-ethyl-1,3-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol (molecular weight: 300 to 6000), tripropylene glycol, 2-butyl-2-hexyl-1,3-propanediol, bishydroxyethoxybenzene, bisphenol A, hydrogenated bisphenol A, hydroquinone, alkylene oxide adducts thereof, and the like, One or more glycols selected from these glycols may be used.
As the glycols, preferred are aliphatic glycols having 4 to 9 carbon atoms, and examples thereof include 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2-methyl-1,8-octanediol, 2,4-diethyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, and diol isomers thereof. Particularly preferred is 1,4-butanediol alone or a mixture of 1,4-butanediol and 1,6-hexanediol.
As the polyisocyanate compound (B) for use as a starting material of the polyurethane resin of the invention, preferably used is an aliphatic and/or alicyclic polyisocyanate compound, and examples thereof include tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,3- or 1,4-bis-(isocyanatomethyl)-cyclohexane, hydrogenated xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 4,4xe2x80x2-dicyclohexylmethane diisocyanate, 2- or 4-isocyanatocyclohexyl-2xe2x80x2-isocyanatocyclohexylmethane, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-dicyclohexylmethane diisocyanate, 2,5(2,6)-bis(isocyanato)methylbicyclo[2.2.1]heptane, and the like. These compounds may be used singly or in combination.
A polyisocyanate compound other than the above polyisocyanate compound may be used in combination unless the effects of the invention are deteriorated. Examples of the former compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyante, p-phenylene diisocyanate, 4,4xe2x80x2-diphenylmethane diisocyanate, 2,4xe2x80x2-diphenylmethane diisocyanate, 2,3xe2x80x2-diphenylmethane diisocyanate, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-biphenylene diisocyanate, 3,3xe2x80x2-dimethoxy-4,4xe2x80x2-biphenylene diisocyanate, 3,3xe2x80x2-dichloro-4,4xe2x80x2-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, and the like.
Furthermore, a polyol (A3) other than the above polycarbonate polyol may be used in combination with the polycarbonate polyol (A2) for use in the invention depending on the use of the polyurethane resin unless the effects of the invention are deteriorated. Examples of such polyol include, as polyester, dehydrative condensation products of glycol components such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 2,2-dimethyl-1,3-propanediol, and the like in addition to the glycols for use as the staring material for the production of the above aliphatic polycarbonate polyol and the glycols having a spiro ring, with acid components such as succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, maleic anhydride, fumaric acid, hexahydroisophthalic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,pxe2x80x2-dicarboxylic acid, and acid anhydrides or ester-forming derivatives of these dicarboxylic acids; p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and ester-forming derivatives of these hydroxycarboxylic acids; or the like. In addition, polyesters and copolymeric polyesters obtainable by the ring-opening polymerization of cyclic esters such as xcex3-butyrolactone and xcex5-caprolactone using the above glycols as initiators may be mentioned. As polyether polyols, there may be mentioned homopolymers or copolymers obtainable by the ring-opening polymerization of ethylene oxide, propylene oxide, butylene oxide, and styrene oxide. Also mentioned is the ring-opening polymerization product of tetrahydrofuran. In addition, aromatic polycarbonate polyols, polyacetal polyols, polyacrylate polyols, polyesteramide polyols, polythioether polyols, and the like may be mentioned.
The chain-extending agent (C) for use in the invention contains preferably a diamine compound as an essential component, and specific examples of the agent include, in addition to the glycols described in the paragraph of the polyester polyols, polyhydroxy compounds such as glycerol, trimethylolethane, trimethylolpropane, sorbitol, and pentaerythritol; polyamine compounds including diamines such as ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,6-hexamethylenediamine, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, N,Nxe2x80x2-diaminopiperazine, isophoronediamine, 4,4xe2x80x2-diaminodicyclohexylmethane, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-diaminodicyclohexylmethane, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, aminoethylethanolamine, aminopropylethanolamine, aminohexylethanolamine, aminoethylpropanolamine, aminopropylpropanolamine, and aminohexylpropanolamine; polyamines such as diethylenetriamine, dipropylenetriamine, and triethylenetetramine; hydrazines; acid hydrazides; and the like. These compounds may be used solely or in combination.
The amount of the polyisocyanate compound (B) for use in the invention is preferably from 0.9 to 1.1 equivalents when the amount of total active hydrogen of the above (A1), (A2), other polyol (A3), and the chain-extending agent (C) is determined as 1 equivalent.
The above components (A), (B), (A3) and (C) can be reacted in accordance with a hitherto known method. For example, the reaction may be carried out without solvent or in an organic solvent or in water at a reaction temperature of 30 to 250xc2x0 C. Preferably, the reaction is carried out in a solvent.
In the case of the solution reaction, an organic solvent, e.g., an aromatic hydrocarbon such as toluene or xylene; a ketone such as acetone, methyl ethyl ketone, or cyclohexanone; an ether such as tetrahydrofuran; an acetate ester such as ethyl acetate or butyl acetate; an amide such as dimethylformamide or 1-methyl-2-pyrrolidone; isopropanol, cellosolve, cellosolve acetate, or the like, may be added at any stage of the beginning of the reaction, the midst of the reaction, and the end of the reaction. The resin composition of the invention is preferably a polyurethane resin solution in a solvent.
At the production of the polyurethane resin of the invention, a monoalcohol, an alcohol having three or more functional groups, an organic monoamine, an amine having three or more functional groups, an organic monoisocyanate, or a polyisocyanate having three or more functional groups may be used, if necessary.
At the production of the polyurethane resin of the invention, a catalyst or a stabilizer may be used, if necessary. These catalyst and stabilizer may be added at any stage.
Examples of the catalyst include nitrogen-containing compound such as triethylamine, triethylenediamine, and morpholine; metal salts such as potassium acetate, zinc stearate, and tin octylate; organometallic compounds such as dibutyltin dilaurate; and the like.
As the stabilizer, a stabilizer to ultraviolet ray such as a substituted benzotriazole, a stabilizer to thermal oxidation such as a phenol derivative, or the like may be added.
The polyurethane resin of the invention is preferably obtained as a resin solution, and the number-average molecular weight measured on GPC is preferably from 5000 to 1000000, By the way, according to the method for producing a polyurethane resin of the invention, a polyurethane resin having a molecular weight out of the above number-average molecular weight range can be obtained, and the polyurethane resin may be used for various uses as far as the resin achieves the effects of the invention.
Other than the above catalyst and stabilizer, additives such as an other resin, an antioxidant, an ultraviolet absorber, a hydrolysis inhibitor, a pigment, a dye, a fire retardant, a filler, and a crosslinking agent may be incorporated, if necessary, into the polyurethane resin or the resin solution obtainable according to the invention.
Examples of the other resin include polyurethane resins other than those of the invention, poly(meth)acrylic resins, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl propionate copolymers, polyvinylbutyral resin, cellulose-type resins, polyester resins, epoxy resins and phenoxy resins, polyamide resins, and the like.
Examples of the crosslinking agent include the above-described organic polyisocyanates, and the like.
A sheet-form article can be formed using the above polyurethane resin or resin composition. At the production of such a sheet-form article, a hitherto known method can be applied to the production depending on the purpose to be used and the method for the production is not particularly limited. Examples thereof include a sheet-form article of a urethane resin film produced from a polyurethane resin solution in a solvent through a wet film-forming process, which is adhered onto one of various base materials such as woven fabrics and non-woven fabrics or without base material; a sheet-form article obtainable by coating one of sheet-form articles formed by various methods with a polyurethane resin solution of the invention through gravure printing, spraying or the like a sheet-form article obtainable by laminating a sheet-form article produced from the polyurethane resin and a sheet-form article prepared by one of other various methods; and the like. Either fine porous polyurethane resin film or non-porous one may be used.
The sheet-form article of the invention means a synthetic leather, an artificial leather, a film, or a sheet for molding, or the like prepared using the polyurethane resin of the invention or its composition. The thickness of the resin film of the sheet-form article is preferably from 0.001 to 3 mm.
In the invention, a compound having one spiro ring and active hydrogen-containing groups at both ends (A1) and an aliphatic polycarbonate polyol (A2) are used, whereby a polyurethane resin excellent in dry touch property and oleic acid-resistance is obtained. Accordingly, it is possible to apply the resin to the uses which require both of dry touch and durability as a sheet-form article such as a synthetic leather, an artificial leather, a film, or a sheet for molding or as a surface layer obtainable by coating the surface of such a sheet-form article.